The present invention relates to a novel color-developing agent, and a silver halide photographic light-sensitive material and image-forming method using the color-developing agent. More specifically, the present invention relates to a silver halide photographic light-sensitive material and image-forming method good in color-forming property at the time of development.
Further, the present invention relates to a novel 1,2,4-oxadiazolyl azo dye, which exhibits excellent absorption characteristics, and which is high in fastness to light, heat, humidity, air, chemicals and the like.
Further, the present invention relates to a silver halide color light-sensitive material containing an image-forming compound containing the novel 1,2,4-oxadiazolyl azo dye or a precursor thereof.
In a color photographic light-sensitive material, when the light-sensitive material is exposed to light and thereafter subjected to color-development, the resultant oxidized color-developing agent reacts with a coupler, to form a dye image.
The color-development is attained, for example, by dipping an exposed light-sensitive material in an aqueous alkaline solution (a developing solution) in which a color-developing agent is dissolved. However, this technique have many problems, for example, a problem that the developing solution tends to be deteriorated with the lapse of time and problems concerning treatments of developing solution wastes.
As one measure to solve above problems, a method wherein an aromatic primary amine developing agent or its precursor is built in the hydrophilic colloid layer of a light-sensitive material is proposed. Further, a method wherein a sulfonylhydrazine-type developing agent is built in the hydrophilic colloid layer of a light-sensitive material is proposed. Examples of these include methods described, for example, in U.S. Pat. No. 803,783, JP-B-58-14671 (xe2x80x9cJP-Bxe2x80x9d means examined Japanese patent publication), European Patent Nos. 545 491(A1) and 565 165(A1).
However, even these methods cannot attain satisfactory color formation when color-developed; and there is the problem of storage stability of the light-sensitive material.
In the fields of silver halide photographic light-sensitive materials, a so-called color diffusion transfer method in which a diffusible dye is formed imagewise on a light-sensitive material and the image is transferred and fixed to an image-receiving material, to form a color image, is a known technique, and many proposals concerned this have been made. In these methods, a compound (a preformed dye) obtained by causing an image-forming dye, which is beforehand colored to have nondiffusibility (the compound will be referred to as a colorant hereinafter), is generally used. Therefore, when the colorant is added to the same layer containing a silver halide emulsion, an undesired drop in the sensitivity to exposure is caused, because of a filter effect of the dye moiety. In order to improve these drawbacks, a so-called coupling system is proposed in U.S. Pat. No. 4,469,773 and JP-B-63-36487 in which system a dye is formed by a coupling reaction between an oxidized product of a developing agent, which is produced as a function of the developing of silver halide, and a coupler. However, the color-developing agent described therein has a difficulty in the compatibility of the storage stability and the activity of the coupling reaction and a difficulty in modifying both the color-developing agent and the coupler to those having resistance to diffusion.
Novel color-developing agents are proposed in JP-A-09-152702 (xe2x80x9cJP-Axe2x80x9d means unexamined published Japanese patent application) and JP-A-09-152705. In these methods, however, sufficient color-forming property is not obtained yet. Also, whether or not there are problems concerning the hue and color image stability of a dye to be formed.
Hitherto, color diffusion transfer photography, using an azo dye image-forming compound that can supply an azo dye having a diffusibility different from the image-forming compound itself, as a result of development under a basic condition, has been widely known. For example, image-forming compounds that release a yellow dye are described in JP-A-52-7727 and JP-A-54-79031, and U.S. Pat. No. 4,473,672. Also, image-forming compounds that release a magenta dye are described, for example, in JP-A-49-114424, JP-A-4-331954, and U.S. Pat. No. 3,932,380
However, these yellow and magenta dye image-forming compounds have insufficient spectral characteristics of the resultant dye resulting in problems in color reproducibility, or they have low fastness to light, heat, air, chemicals, and the like. Thus, yellow or magenta dye image-forming compounds satisfying all performance requirements have not yet been found, and further improvement has been desired.
The present invention is a color-developing agent represented by the following formula (1-1): 
wherein X represents a hydrogen atom or a substituent, and Z represents a carbamoyl, acyl, alkoxycarbonyl, or aryloxycarbonyl group.
Further the present invention is a silver halide photographic light-sensitive material, which contains at least one color-developing agent represented by the formula (1-1) on a support.
Further, the present invention is an image-forming method, which comprises the step of subjecting the silver halide photographic light-sensitive material to heat-development.
Further, the present invention is an image-forming method, which comprises the step of subjecting the silver halide photographic light-sensitive material to development, under generation of an alkali by a slightly soluble metal salt and a complexing agent of the metal salt.
Further, the present invention is an image-forming method, which comprises the step of subjecting the silver halide photographic light-sensitive material to development by developing an alkaline processing solution.
Further, the present invention is an azo dye represented by the following formula (2-1): 
wherein R1 represents a hydrogen atom or a substituent, and A represents a group of atoms necessary for formation of the azo dye by the compound of the formula (2-1).
Further, the present invention is a silver halide photographic light-sensitive material, which contains the azo dye represented by the formula (2-1).
Further, the present invention is a silver halide color photographic light-sensitive material, which contains at least one dye-forming compound represented by the following formula (2-5) on a support:
(Dye)q-X1xe2x80x94Yxe2x80x83xe2x80x83formula (2-5) 
wherein Dye represents an azo dye represented by the formula (2-1) or azo dye precursor thereof, X1 represents a single bond or a connecting group which is cleaved in correspondence to or in inverse correspondence to development, Y represents a group which has a nature of generating a difference in diffusibility of the dye component in correspondence to or in inverse correspondence to reaction of a light-sensitive silver salt having a latent image imagewise, Dye is bonded to X1 at a position or positions of at least one of R1 and A in the formula (2-1), q is 1 or 2, and when q is 2, Dye""s may be the same or different.
Other and further features and advantages of the invention will appear more fully from the following description, taken in connection with the accompanying drawing.